As a reduction in the feature size of circuit patterns formed in a semiconductor wafer progresses, the effect on the product yield, which defects generated in manufacturing processes have, increases. It is therefore increasingly important to manage the manufacturing processes so that such a defect is not generated in the manufacturing stage. Today, at the manufacture sites of semiconductor wafers, yield improvement measures are usually taken using a defect check device and a defect inspection device. The defect check device is a device that images the state of a wafer surface using an optical unit or an electron beam and automatically processing the resulting image, thereby quickly investigates which position on a wafer a defect is present at. In such a defect check device, the quickness is important, and therefore the amount of image data is reduced by increasing the pixel size (i.e., by a reduction in resolution) of an image obtained, as much as possible. In many cases, from a detected image of a low resolution, the presence of a defect might be confirmed but the type of the defect cannot be determined in detail.
On the other hand, the defect inspection device (review device) is a device that is used to obtain and inspect an image with the pixel size reduced (i.e., with a high resolution) for each defect detected by a defect check device. Such a defect inspection device is already brought to the market by a plurality of manufacturers, today. Some devices have a function to automatically classify captured images in order to help to identify the cause of a defect.
In the semiconductor manufacturing process in which a reduction in feature sizes increasingly progresses, the defect size may reach an order of tens of nanometers, and the resolution on the order of nanometers is required in order to inspect or classify defects. For this reason, in recent years, the defect inspection device using a scanning electron microscope is beginning to be widely used. Moreover, in the mass production line of semiconductor devices, streamlining of the inspection work (review work) of defects is desired, so a defect inspection device has started to have a function to automatically capture the image at a defect position detected by a defect check device (an ADR function: Automatic Defect Review function) or a function to classify the obtained images (an ADC function: Automatic Defect Classification function).
In semiconductor mass production lines, the occurrence of a defect in a manufacturing process needs to be properly monitored. Therefore, with regard to as many wafers as possible, the inspection by a defect check device and the inspection and classification of defects by a review SEM that is the defect inspection device need to be carried out, and thus in the defect check device and the review SEM, an improvement in the processing speed, i.e., the throughput, becomes particularly important. The throughput in the review SEM implies the number of defects that can be imaged and classified within a unit of time. The throughput of the review SEM brought to the market today is 1000-2000 [defects/time]. The throughput performance has been dramatically improving, and is more likely to be further increased in future, as well. A conventional art with regard to the function and the like of such a review SEM is disclosed in JP-A-2001-331784 (Patent Literature 1). Patent Literature 1 describes the configuration of a review SEM, the functions and operation sequences of ADR and ADC, and furthermore a method for displaying an obtained image or a classified result, and the like.
In order to detect a very fine defect in a visual check of semiconductors, a high resolution image captured by an electron beam microscope may be used. However, in inspection using the electron beam microscope, the detection of a very fine defect and the inspection at high speed cannot be combined, and therefore programmed-point inspection (fixed-point check) is performed, wherein inspection points within a chip are determined in advance and the check of the same inspection point of all the chips or selected chips within a wafer is performed. If this fixed-point check is performed by image comparison with a golden pattern image, highly sensitive inspection can be realized. By using the fixed-point check using an electron beam microscope in an early phase of semiconductor process development, external appearance information about a generated defect and information about a defect distribution within a wafer surface can be obtained, thus enabling to efficiently perform process conditioning.
As the literatures related to this, Patent Literature 2 discloses a comparison check method using a golden pattern image, as the programmed point inspection method using an electron beam microscope. Moreover, non-Patent Literature 1 discloses an example of characterizing a defect by using an inspection image, as the programmed point inspection method using an electron beam microscope.